Air conditioning unit



July 1, 1969 M. G. YERDON ETAL AIR CONDITIONING UNIT Filec} April 27, 1967 FIG. I

INVENTORS.

G. YERDON. HONNOLD, JR. 5%

ATTQENE! MICHAEL BY FRED V United States Patent US. Cl. 165-37 3 Claims ABSTRACT OF THE DISCLOSURE An induction type room terminal for use in an air conditioning system employing an improved bellows actuated damper assembly for regulating the amount or room air induced therethrough.

Background 07 the invention This invention relates to air conditioning units, and more particularly to air conditioning units of the induction type wherein a first volume of air (primary air) is conditioned at a central station and distributed at relatively high static pressure and relatively high velocity for discharge therein through nozzles or the like to induce a quantity of room air (secondary air) to circulate therethrough. The primary and secondary air mixture is then supplied to the conditioned area. A heat exchanger supplied with a conditioning medium is provided in each unit to effect sensible cooling or heating of the air circulated through the unit as required. A damper is provided in the unit for regulating the quantity of secondary air passing through or around the heat exchanger, spring means being provided for urging the damper in a first direction to increase the passage of secondary air through the heat exchanger. Bladder means are provided for actuating the damper in response to a regulating control air pressure to decrease the quantity of air passing through the heat exchanger and increase the quantity of air bypassing the heat exchanger. A bleed type thermostat responsive to the temperature of the secondary air regulates the control air supplied to the bladder. It is common practice to utilize the induction units in both vertical and horizontal orientations.

Numerous problems have been encountered with the damper mechanism employed to regulate secondary air flow through the unit. Primary air is commonly utilized as the control air for actuating the damper mechanism. As such, the damper mechanism must be free to operate with very little resistance. When the damper is open to allow passage of secondary air through the heat exchanger, the air flow along the face thereof tends to cause the damper to assume a slightly closed position due to the reduced pressure on the face thereof caused by the moving air stream. The spring or other means provided to maintain the damper in the open position must be therefore strong enough to counteract the aforementioned action plus the gravity force acting on the blade while providing minimal resistance to damper closing under the influence of the control air pressure and associated bladder. Another complication is added when an induction unit is utilized in a horizontal position as counterweights are usually necessary on the damper to supplement the damper opening spring force. Consequently, the optimum spring force could not always be achieved due to the required compromises. Further, since the control air pressure supplied to the bladder varies somewhat from system to system, the spring force had to be adjustable on induction units heretofore available to insure proper damper operation.

Summary of the invention In accordance with the preferred embodiment of this invention, an air conditioning unit is provided which employs an improved damper mechanism having low friction pivot means therefor and a leaf spring have one end attached to the damper blade substantially normal to the plane thereof. A socket is provided on a portion of the air conditioning unit for engagement with the other end of the spring, engagement of the spring in the socket causing the spring to assume an arched position to exert a great enough force on the damper blade to prevent its movement toward closed position under the influence of the secondary air stream flowing across its face, plus the blade gravity force, while providing an opening force small enough to allow the damper to be easily closed by the bladder under the influence of control air.

Brief description of the lirawings FIGURE 1 is a sectional end view of an induction type 'room terminal within a cabinet showing the bypass damper in open position;

FIGURE 2 is a fragmentary sectional end view of a vertical induction type room terminal showing the bypass damper in closed position; and

FIGURE 3 is a fragmentary sectional view taken along line IIIIII of FIGURE 1 illustrating the damper pivot construction and spring mount.

Description of the preferred embodiment Referring to the drawings, there is illustrated an induction type air conditioning unit. The unit includes a casing 3 having a secondary air inlet 5 in the lower portion of casing front panel 7 and an air outlet 9 in casing top panel The unit includes an enclosure 17 forming a plenum from which primary air is discharged through horizontally spaced nozzles 19 which provide high kinetic energy jet streams of air passing upwardly in a generally vertical passage 21 formed between casing front panel 18 and the plenum enclosure 17 to induce the flow of secondary air therethrough. From the inlet 5, the secondary air passes into an area 23 defined by inclined heat exchanger coil 25, base panel 27 and bypass inlet 29 formed between the bottom of the heat exchanger 25. and casing base panel 27. The flow of secondary air through the coil 25 and the bypass inlet 29 is regulated by a damper assembly 31. The mixture of primary and secondary air is discharged into the room through the air outlet 9 which communicates with passage 21.

The plenum enclosure 17 is divided into an upper section and a lower section by an adjustable damper 39. The plenum enclosure has openings at both ends (not shown) communicating with the upper section of plenum enclosure 17 for connection to plenums of other base units and a source of primary air. The desired static pressure can be maintained in the lower section of plenum 17 by adjustment of damper 39 to provide a desired flow rate of primary air through the nozzles 19 which are mounted on the plenum enclosure in communication with the lower section thereof.

The damper assembly 31 includes a damper blade 41 having a generally flat section 43, an angled flange sec tion 44 at one end thereof, and a channel section 45 at the other end. The blade 41 may be modulated between the closed position, as shown in FIGURE 2., and fully open position, as shown in FIGURE 1.

In the closed position, the damper blade 41 prevents the passage of secondary air through the coil 25 causing the secondary air to pass through bypass inlet 29 so that the temperature of the secondary air is substantially unaffected by the coil 25. In the fully opened position, the

damper blade 41 prevents the flow of secondary air through the bypass inlet 29, causing all of the secondary air to flow through coil 25. Modulation of the damper blade 41 between these two positions is provided by a bladder 36, which, when inflated, closes the damper, and leaf spring 47 which biases the damper open.

A mounting bracket 49 is suitably affixed to blade 41, as by welding, for attachment thereto of leaf spring 47 substantially normal to the plane of blade 41. A socket 51 suitably afiixed to front panel 18, as by rivets 55, is provided for engagement with rounded clip 57 on the other end of spring 47. The channel section 45 formed in blade 41 is provided for mounting pivot blocks 61 for engagement with low friction bearing grommets 63 pressed into end plates 65 of the unit.

A polyurethane sealing strip 69 is adhesively secured to front panel 18 for engagement with lip 71 formed on blade 41 to provide a seal therebetween when the damper is in closed position. A second polyurethane sealing strip 73 is adhesively secured to the bottom portion of plenum enclosure 17 to provide a seal with lip 71 when the damper is in open position to prevent secondary air from bypassing coil 25.

Thebladder 36 which is made of a suitable flexible plastic material is mounted on channel member 75 which is removably secured at both ends to end plates 65 as by studs and wing nuts 77. Bladder 36 is adhesively afiixed to channel member 75. A connector 79 having a passageway therethrough which communicates with the interior of bladder 36 is provided for connection to a suitable source of control air for modulated inflation of bladder 36 to position damper 41 for proportioning the secondary air through coil and bypass inlet 29.

In an air conditioning unit of the type described, the damper assembly must be capable of operating properly under a variety of adverse conditions characteristic of bypass terminals.

When the damper is fully open, as illustrated in FIG- URE 1, the air flow across the damper face cause a closing force to be exerted on the damper blade. The spring must be strong enough to counteract this force. Due to the fact that the closing force exerted on the damper by the bladder decreases as the damper is moved toward closed position and the opening spring force works in opposition to the bladder as does the lift force due to air flow when the damper is in a substantially open position, the spring force must be minimized for closing the damper. However, if the air flow through the unit is cut off, the spring must be strong enough to return the damper from closed position to open position against the force of gravity to allow gravity flow of air through the unit and across the heat exchanger.

Our invention provides a damper which is subjected to a non-linear spring force which results in a damper mechanism that is operable over a wide range of control air pressure and performs properly under all of the aforementioned conditions.

A further advantage of our invention is that damper counterweights are not necessary when the unit is utilized in --a horizontal position. The use of a spring having a greater stiffness than those used in the vertical units is sufficient to overcome the added gravity force on the damper.

While a preferred embodiment of this invention has been described and illustrated, it should be understood that the invention is not limited thereto but may be otherwise embodied within the scope of the following claims.

We claim:

1. In an air conditioning unit, the combination of a casing, a plenum enclosure in said casing adapted to be placed in communication with a source of supply air, said plenum enclosure having discharge means therein to discharge primary air within the casing, a heat exchanger in said casing adapted to be placed in communication with a source of heat exchange medium, said casing having an inlet and an outlet therein, discharge of primary air in the unit inducing secondary air from the area being conditioned through the inlet into the unit to mix with primary air, the mixture being discharged from the outlet, a damper movable between an open and a closed position for regulating the quantity of secondary air passing through the heat exchanger, means pivotally mounting said damper in said casing, spring means for exerting a non-linear opening force on said damper, and expansible means for moving said damper closed against the force of said spring means.

2. An air conditioning unit according to claim 1 whereinsaid spring means includes socket means aflixed to said casing, and a leaf spring having one end affixed to said damper substantially perpendicular thereto and the other end bearing against said socket means, causing said spring to assume an arched position to bias said damper open.

3. An air conditioning unit according to claim 1 wherein said pivot means includes grommet means afiixed to opposite ends of said casing and, pivot pins, attached to said damper and journaled in said grommets for rotation therein.

References Cited UNITED STATES PATENTS 1,942,137 1/1934 Cornell et a1. 98--40 X 3,196,498 7/1965 Hochuli et al. 98-121 X 3,198,246 8/1965 Brown et al. l35 3,208,508 9/1965 Bryans et al -423 MEYER PERLIN, Primary Examiner.

T. W. STREULE, Assistant Examiner.

' US. Cl. X.R. 165--123 

